System and method for traffic sign recognition
First Claim
1. A vehicle-mounted traffic sign recognition system comprising:
- a forward-looking camera configured to capture stream data of imagery containing image frames having traffic sign images therein;
a rotation and scale-invariant geometric pattern-matching process constructed and arranged to identify traffic sign candidates in the stream data, the geometric pattern-matching process including a pre-training mechanism to pre-train with predetermined traffic sign models having exterior geometric features and to classify each of the traffic sign candidates as either an unrecognized object or as a sign of a predetermined type upon a high-confidence match between each of the traffic sign candidates and at least one of predetermined traffic sign models, and wherein the geometric pattern-matching process also produces pose information concerning the traffic sign candidates including at least one of a position, scale, skew and rotation with respect to at least one of the predetermined traffic sig models matched; and
with a plurality of discrimination processes, analyzing, in succession, each of the traffic sign candidates received from the traffic sign candidate producer with respect to pre-trained traffic sign features to either increase or decrease a confidence level in each of the traffic sign candidates, and passing or failing each of the traffic sign candidates based upon the confidence level, and associating passed traffic sign candidates with a predetermined type of traffic sign for use by the method, the plurality of discrimination processes including at least two of;
a) a color discrimination process that compares a color in a closed geometric shape of each of the traffic sign candidates to color features in an associated model from the pre-trained traffic sign features,b) a pose discrimination process that compares a pose of each of the traffic sign candidates to pose features in an associated model from the pre-trained traffic sign features, andc) a fascia discrimination process that compares predetermined fascia features of each of the traffic sign candidates in a current pose to fascia features in an associated model from the pre-trained traffic sign features to determine a subtype of a sign candidate based upon an identified fascia matching the model from the pre-trained traffic sign features.
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Abstract
This invention provides a vehicle-borne system and method for traffic sign recognition that provides greater accuracy and efficiency in the location and classification of various types of traffic signs by employing rotation and scale-invariant (RSI)-based geometric pattern-matching on candidate traffic signs acquired by a vehicle-mounted forward-looking camera and applying one or more discrimination processes to the recognized sign candidates from the pattern-matching process to increase or decrease the confidence of the recognition. These discrimination processes include discrimination based upon sign color versus model sign color arrangements, discrimination based upon the pose of the sign candidate versus vehicle location and/or changes in the pose between image frames, and/or discrimination of the sign candidate versus stored models of fascia characteristics. The sign candidates that pass with high confidence are classified based upon the associated model data and the drive/vehicle is informed of their presence. In an illustrative embodiment, a preprocess step converts a color image of the sign candidates into a grayscale image in which the contrast between sign colors is appropriate enhanced to assist the pattern-matching process.
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Citations
22 Claims
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1. A vehicle-mounted traffic sign recognition system comprising:
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a forward-looking camera configured to capture stream data of imagery containing image frames having traffic sign images therein; a rotation and scale-invariant geometric pattern-matching process constructed and arranged to identify traffic sign candidates in the stream data, the geometric pattern-matching process including a pre-training mechanism to pre-train with predetermined traffic sign models having exterior geometric features and to classify each of the traffic sign candidates as either an unrecognized object or as a sign of a predetermined type upon a high-confidence match between each of the traffic sign candidates and at least one of predetermined traffic sign models, and wherein the geometric pattern-matching process also produces pose information concerning the traffic sign candidates including at least one of a position, scale, skew and rotation with respect to at least one of the predetermined traffic sig models matched; and with a plurality of discrimination processes, analyzing, in succession, each of the traffic sign candidates received from the traffic sign candidate producer with respect to pre-trained traffic sign features to either increase or decrease a confidence level in each of the traffic sign candidates, and passing or failing each of the traffic sign candidates based upon the confidence level, and associating passed traffic sign candidates with a predetermined type of traffic sign for use by the method, the plurality of discrimination processes including at least two of; a) a color discrimination process that compares a color in a closed geometric shape of each of the traffic sign candidates to color features in an associated model from the pre-trained traffic sign features, b) a pose discrimination process that compares a pose of each of the traffic sign candidates to pose features in an associated model from the pre-trained traffic sign features, and c) a fascia discrimination process that compares predetermined fascia features of each of the traffic sign candidates in a current pose to fascia features in an associated model from the pre-trained traffic sign features to determine a subtype of a sign candidate based upon an identified fascia matching the model from the pre-trained traffic sign features. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for recognizing traffic signs from a vehicle comprising the steps of:
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capturing stream data of imagery containing image frames having traffic sign images therein; identifying, with a rotation and scale-invariant geometric pattern-matching process, traffic sign candidates in the stream data, the geometric pattern-matching process including a pre-training mechanism to pre-train with predetermined traffic sign models having exterior geometric features and classifying each of the traffic sign candidates as either an unrecognized object or as a sign of a predetermined type upon a high-confidence match between the each of the traffic sign candidates and at least one of predetermined traffic sign models, and wherein the geometric pattern-matching process also produces pose information concerning the traffic sign candidates including at least one of a position, scale, skew and rotation with respect to at least one of the predetermined traffic sign models matched; and with a plurality of discrimination processes, analyzing, in succession, each of the traffic sign candidates received from the traffic sign candidate producer with respect to pre-trained traffic sign features to either increase or decrease a confidence level in each of the traffic sign candidates, and passing or failing each of the traffic sign candidates based upon the confidence level, and associating passed traffic sign candidates with a predetermined type of traffic sign for use by the method, the plurality of discrimination processes including at least two of; a) a color discrimination process that compares a color in a closed geometric shape of each of the traffic sign candidates to color features in an associated model from the pre-trained traffic sign features, b) a pose discrimination process that compares a pose of each of the traffic sign candidates to pose features in an associated model from the pre-trained traffic sign features, and c) a fascia discrimination process that compares predetermined fascia features of each of the traffic sign candidates in a current pose to fascia features in an associated model from the pre-trained traffic sign features to determine a subtype of a sign candidate based upon an identified fascia matching the model from the pre-trained traffic sign features. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification